Zhaosu, a county located deep in the Tianshan Mountains, is becoming a popular winter tourism attraction. The temperature in Zhaosu drops to minus 15 degrees Celsius in January, freezing up the turquoise Yuhu Lake and trapping thousands of white bubbles below the surface. Those frozen bubbles are formed when plants at the bottom of the lake start decaying. During the process, methane and carbon dioxide are released, creating bubbles in the water. When the temperature plunges, these bubbles start to surface and become trapped in the thickening ice, suspended just below the surface of the water.